{"id":3782,"date":"2024-10-28T11:55:45","date_gmt":"2024-10-28T11:55:45","guid":{"rendered":"https:\/\/raspberry-projects.com\/pi\/?p=3782"},"modified":"2024-10-28T13:32:28","modified_gmt":"2024-10-28T13:32:28","slug":"using-the-spi-interface-2","status":"publish","type":"post","link":"https:\/\/raspberry-projects.com\/pi\/programming-in-python\/spi-programming-in-python\/using-the-spi-interface-2","title":{"rendered":"Using the SPI Interface"},"content":{"rendered":"\n<h4 class=\"wp-block-heading\">Enabling The SPI Port<\/h4>\n\n\n\n<p>The SPI port needs to be enabled in Raspberry Pi OS before it can be used. See <a href=\"\/pi\/pi-operating-systems\/raspbian\/io-pins-raspbian\/spi-pins\">here<\/a>.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Test the SPI Port<\/h4>\n\n\n\n<p>Test the SPI port is working on the command line by typing:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>ls \/dev\/spidev*<\/code><\/pre>\n\n\n\n<p>You should see the following:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/dev\/spidev0.0  \/dev\/spidev0.1<\/code><\/pre>\n\n\n\n<p>There are 2&nbsp;spidev devices shown (or more on newer Pi&#8217;s). &nbsp;The first number refers to the SPI peripheral which in both cases is 0 (the RPi only has 1&nbsp;SPI&nbsp;port), the second number represents the chip select pins&nbsp;CS0 and CS1 .<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Install spi library<\/h4>\n\n\n\n<p>May well already be present with Raspberry Pi OS, but if you need to:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>sudo apt-get update\nsudo apt-get upgrade\nsudo apt install python3-spidev<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\">SPI access<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>#!\/usr\/bin\/python\n\nimport spidev\n\nbus = 0\t\t\t\t\t\t#Select SPI bus 0\ndevice_cs = 1\t\t\t\t#CS pin. Select 0 or 1, depending on the connection to the RPi\nspi = spidev.SpiDev()\t\t# Enable SPI\nspi.open(bus, device_cs)\t#Open connection to the device\nspi.max_speed_hz = 500000\nspi.mode = 0\n\n\n#Send a byte\ndata_tx = &#91;0x76]\nspi.xfer2(data_tx)\n\n#Send and receive a byte\ndata_tx = &#91;0x00]\ndata_rx = spi.xfer2(data_tx)\n\n\n#Send and receive bytes\ndata_tx = &#91;0x24, 0x33, 0x18]\ndata_rx = spi.xfer2(data_tx)\nif (data_rx&#91;0] == 0x11):\n\tpass<\/code><\/pre>\n\n\n\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Enabling The SPI Port The SPI port needs to be enabled in Raspberry Pi OS before it can be used. See here. Test the SPI Port Test the SPI port is working on the command line by typing: You should see the following: There are 2&nbsp;spidev devices shown (or more on newer Pi&#8217;s). &nbsp;The first [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[193],"tags":[],"class_list":["post-3782","post","type-post","status-publish","format-standard","hentry","category-spi-programming-in-python"],"_links":{"self":[{"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/posts\/3782","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/comments?post=3782"}],"version-history":[{"count":4,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/posts\/3782\/revisions"}],"predecessor-version":[{"id":3791,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/posts\/3782\/revisions\/3791"}],"wp:attachment":[{"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/media?parent=3782"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/categories?post=3782"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/raspberry-projects.com\/pi\/wp-json\/wp\/v2\/tags?post=3782"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}